The present invention concerns a hinge for a roof window with a sash pivoting around an axis located between the upper and the lower member of a window.
A roof window with a pivot function is at both sides equipped with pivot hinges, comprising two hinge parts, one hinge part secured to the side member of a window frame, and the other hinge part secured to the side member of a sash. Each hinge part has a base plate for securement by fastening screws through screw holes.
One side of each base plate has additional means for securing the plate to a window frame or a sash and the other side of the base plate has members mating one another, which connect both plates, enabling their separation, and enable pivoting of the base plates relative to each other. The members constitute: an arched, one-sided open guide with a friction spring located on the base plate secured to a window frame, and a pivoting hook with an arch-bent arm, a guide pin and a bumper for limiting hook pivoting located on the base plate secured to a sash, at the same time the arm-bent hook arm and the guide pin mate the arched guide and the friction spring.
Pivot hinges in roof windows are secured between the upper and the lower window member, usually in a place that ensures the balance of a sash in the open position of a window. The balance is achieved when the centre of gravity of a window sash is in its rotation axis or in such a distance from the rotation axis that the hinge friction spring is able to keep an unbalanced sash in any rotational position. Therefore the rotation axis of a roof window sash is usually located at a little distance from the half of the window height. A bigger shift of the sash rotation axis or any additional equipment on any of its parts, the lower or the upper, disturbs the balance and causes that a window is unable to hold its sash in each ajar position and a user operating the window has to use more strength to overcome the unbalanced weight of the sash.
A roof pivot window is known from applications WO2005/019574, which is equipped with a known pivot hinge, of the rotation axis located in the upper half of a window, sash, in addition it is equipped with at least one auxiliary device independent from the hinge, presented as a cylinder, which carries the lower, heavier part of a window sash. The device is at one end secured to a window frame and at the other end it is secured to a window sash, in addition the securement allows to separate the device from the window frame.
The auxiliary device constitutes an additional fixture of a roof window and it requires performing of additional activities during assembly of a window and during installation of a window in a roof, it deteriorates aesthetics of the window in an ajar position of the sash, moreover if the need arises to remove a sash from a window frame the cylinder must be disconnected from the window frame beforehand.